Some peripheral wireless devices, such as mobile communication devices or personal data assistants, have at least two wireless communication subsystems (or modules) that both include a radio that can receive and send data wirelessly. Another example includes personal computers or laptops with Wireless Local Area Network (WLAN) internet access and a Bluetooth (BT) connection to input device such as a mouse. Other examples include a laptop or cellular telephone with WLAN access and a BT-enabled headset. The two radios may generally operate within the same frequency bands, in which case it is important for the two communication modules to operate such that they do not interfere with one another.
In one example, a mobile communication device can include a long-range wireless radio, and a short-range wireless radio. An example of a long-range wireless radio is a WLAN radio. An example of a short-range wireless radio is a BT radio. Generally, a BT radio can transmit a signal that collides with a WLAN signal. However, for BT audio transmission or Voice-Over-IP (VoIP) over WLAN, error packet rates greater than a few percent can cause intolerable audio delays or dropped calls.
Currently there are several time-only or frequency-only based methods for supporting co-location of these radios. Examples of time-only based methods are Packet Transmission Arbitration (PTA) algorithms, which allow time division of the shared frequency spectrum. Examples of frequency-only based methods are pseudo-random Adaptive Frequency Hopping (AFH) algorithms that can be used by the BT radio to avoid interference with the WLAN radio. However, these algorithms do not adequately handle transitions by the WLAN radio to a new frequency region or communication channel. For instance, PTA ensures that one radio will not transmit while the other radio is receiving, which would result in loss of reception. AFH can eventually determine that the BT radio is experiencing interference (due to the operation of the WLAN radio) and will avoid the operating frequency region of the WLAN radio, but the time that is required to make this determination and adjustment is too long in some cases. For example, if this situation occurs during a VoIP call, then it will cause voice samples to be missed, since the voice samples have a limited period of time during which they need to be transmitted or received. Further, it is very likely that this time is less than the time required for the AFH algorithms to detect interference and adjust the operating frequency region of the BT radio to exclude the frequency region where interference occurs.